An inflammatory reaction is a series of processes associated with the elimination of foreign matter and pathogens and the protection and repair of tissue. In the course of an inflammatory reaction, there is also a parallel immune reaction that actively eliminates foreign contaminants at the same time. For example, in tissues other than the central nervous system, macrophages ingest and digest bacteria and viruses or dead cells invading into the living body. They also perform antigen presentation, contributing to antibody production by B-cells. In the central nervous system, the role of the macrophages is played by a type of immunocompetent cell called microglia.
Two types of microglia and macrophages are known: the tissue-destroying type and the tissue-repairing type (Non Patent Literature 1, Non Patent Literature 2). The process of eliminating pathogens and protecting tissue in inflammatory reactions is characterized by the aggregation of tissue-destroying microglia and macrophages. However, if excess aggregation occurs it may cause injury to the body's own tissue and increased pain. In the tissue-repairing process, on the other hand, the tissue-repairing microglia and macrophages promote tissue repair.
A composition containing culture supernatant of dental pulp stem cells or other stem cells has been described as effective for treating injuries (Patent Literature 1).